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Body Fat Calculator

Estimate body fat percentage using waist, hip and neck measurements. Understand your body composition and track progress toward your health and fitness goals.

Last reviewed 15 August 2026Reviewed after a methodology change

Your details

Calculator inputs
cm, women

When to use this calculator

  • Before setting a new health goal or checking whether a plan is realistic.
  • When you want a quick baseline before discussing the result with a professional.
  • When you are starting a fitness or diet programme and want a starting measurement.
  • When you want to recheck the numbers after several weeks of change.

A realistic planning example

Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.

A realistic planning example
InputValue
Weight (kg)80 kg
Height (cm)178 cm
Neck Circumference (cm)38
Waist Circumference (cm)84 cm

After entering these figures, review body fat, fat mass and lean mass together rather than in isolation. Then rerun the tool with one input adjusted.

How to read your results

Body Fat

The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.

Fat Mass

The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.

Lean Mass

The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.

Method & assumptionsAuthoritative sources

This calculator estimates body fat percentage using circumference-based measurements, most commonly the US Navy method, which uses measurements of the neck, waist, and hips (for women) alongside height to derive an estimate. The underlying formula was developed and validated by the US Navy as a practical field assessment tool. While it avoids the need for specialist equipment, it is less precise than clinical methods such as DEXA scanning. Circumference measurements are sensitive to measurement technique — small errors in tape placement can shift the result by several percentage points. Treat your result as a useful guide for monitoring trends over time rather than as a clinically precise figure. For accurate body composition assessment, consult a healthcare professional.

Common mistakes

  • !Using an assumption that is not supported by a current local quote, bill, statement or official source.
  • !Treating a generic estimate as a lender, provider, payroll or tax authority decision.
  • !Mixing monthly and annual inputs without converting them consistently.
  • !Testing only one scenario instead of checking how a cautious assumption changes the result.

What to do next

  • Run a second scenario with a cautious assumption so you can see the downside clearly.
  • Compare the result with the related calculators below before making a decision.
  • Check current local rules, eligibility and provider terms before applying or committing money.
  • Keep a record of the assumptions so you can update the estimate when a quote, bill or pay figure changes.

Keep exploring

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Frequently asked

American Council on Exercise ranges: men - essential 2-5%, athletes 6-13%, fitness 14-17%, acceptable 18-24%, obese 25%+. Women - essential 10-13%, athletes 14-20%, fitness 21-24%, acceptable 25-31%, obese 32%+. Women naturally carry more essential fat due to reproductive and hormonal functions.

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